#1. This one came with my DPMS Panther Bull Deluxe. The carrier nearly completely encloses the firing pin as I thought was standard.

#2. This carrier came with a BM M4 upper recently. It appears different in that the bottom of the carrier exposes the firing-pin right up to where it seats into the bolt. Compared to the DPMS, the BM has less 'meat', having a larger cut-out, and ramping up to the bolt.

There are three different types of semi-auto bolt carrier. Go to biggerhammer.net to see the difference between the standard semi-auto and the select-fire bolt carrier.

#1) The standard AR-15 bolt carrier. This is the "mil-spec" carrier used by Bushmaster and most other manufacturers. The back end of the carrier has a small area that is circular. There is a ramp or relief cut on the undersurface leading to the firing pin. Found in early Colts and most others.

#2) Colt HBAR bolt carrier. The back of the carrier is a semi-circle, no complete circle. No firing pin relief cut. I don't know why Colt did this? I guess it made the gun less "evil" like the sear block & all the other Colt BS.

#3) Colt Sporter bolt carrier. Found in all new Colts. The back of the carrier is semi-circular. There is a firing pin relief cut. Again, a abberation unique to Colt.